黔东南凯里-榕江-从江前寒武系甚低级变质作用研究   总被引：1，自引：0，他引：1  

安佳丽  王河锦  苑蕾 《岩石学报》2018,34(3):669-684

根据碎屑岩甚低级变质作用原理,运用伊利石结晶度、绿泥石结晶度、伊利石-白云母多型、伊利石(白云母)b_0值、绿泥石温度计等碎屑岩低温变质研究的方法,分析研究了黔东南前寒武系67个2μm的粘土样品,得到黔东南凯里-榕江-从江一带下江群伊利石结晶度为0.221~0.607°Δ2θCu Kα、绿泥石结晶度为0.239~1.393°Δ2θCu Kα,变质带伊利石-白云母多型均为2M_1型,伊利石(白云母)b_0值为0.9001~0.9048nm,平均0.9021nm。根据伊利石(白云母)b_0值的累积频率曲线得出研究区下江群遭受的变质作用为典型的中压变质类型。由Cathelineau(1988)绿泥石温度计估算出下江群浅变质带峰期变质温度为362~382℃。以上结果表明凯里-榕江-从江一带下江群经历了成岩-高近变质-浅变质作用,基于Warr和Rice标样的成岩/变质界限,剖面可划分为一个成岩带、两个近变质带、一个转变带和一个浅变质带。结合华南地区新元古代构造运动,推断新元古界下江群经历的成岩-变质作用与晋宁运动引起的扬子地块与华夏地块碰撞拼贴有关。  相似文献   

粤西河台金矿田糜棱岩XRD特征及其地质意义     

师爽  龚朝阳  焦骞骞  许德如  张胜印  常华诚  胡彬 《地质论评》2021,67(5):67060006-67060006

粤西河台金矿区位于钦州湾—杭州湾（钦—杭）结合带南段的云开地区,是典型的受韧性剪切带控制的金矿。然而,对于剪切带中有利于金成矿的地质环境及其成矿过程仍然存在争议。本文在对河台矿区高村矿床进行详细野外地质调查的基础上,通过X射线衍射（XRD）对含金剪切带中各类糜棱岩系列岩石进行系统研究,建立应力变化—成分变异的对比序列,从而进一步揭示剪切变形与金矿化的关系。结果显示,剪切带中白（绢）云母的含量在9%~40%,并且在初糜棱岩、无矿糜棱岩、含矿糜棱岩、无矿超糜棱岩、含矿超糜棱岩中含量呈现出逐渐递增的趋势。白（绢）云母主要为2M1型,b0值分布在0.55505~0.99002 nm之间,在初糜棱岩、无矿糜棱岩和无矿超糜棱岩中逐渐增高,分别形成在低压、中压和高压环境。可见,从初糜棱岩到超糜棱岩,随着变形强度的增加,热液活动也随之增强,从而新生成了大量白（绢）云母。然而,在含矿的糜棱岩和超糜棱岩中还存在一些低压白云母,推测其可能是在后期脆性裂隙中由于流体活动所新形成的。因此,成矿可能经历了两个阶段,即早期的韧性剪切变形阶段导致金的初步富集,后期叠加的脆性破裂阶段形成具有工业品位的矿体。另外,无矿超糜棱岩的石英含量（29.8%）明显低于糜棱岩（44.2%）,推测在形成石英脉型矿体过程中,部分热液可能来自于其围岩超糜棱岩。因此,相对于初糜棱岩和糜棱岩,超糜棱岩中更有利于金矿的形成。  相似文献   

靖远地区大厚度黄土地基浸水湿陷过程及土中竖向应力特征试验研究     

刘德仁  安政山  徐硕昌  王旭  张转军  金芯  张严 《岩土力学》2023,44(1):268-278

为了研究靖远大厚度黄土在浸水条件下的水分入渗规律和自重湿陷变形特征,在中兰铁路沿线的靖远北站黄土自重湿陷场地进行了不打注水孔的现场浸水试验,监测并分析了地表及地下湿陷变形、试坑周围裂缝、含水率和土中竖向应力变化情况,对水分扩散规律、自重湿陷特性和土中竖向应力变化规律进行了研究,并对地区修正系数β0值和浸润角进行了探讨。结果表明：体积含水率变化分为浸水稳定（2个）、快速增加（1个）和缓慢增加（1个）共4个阶段;浸水过程中,水分在21m处竖向入渗加快、径向扩散减缓,湿润峰最终形态呈现为椭圆状。根据探井和钻孔含水率测试结果,推算出浸润角最大为41°。该场地黄土自重湿陷过程历经剧烈湿陷、缓慢湿陷和固结稳定3个阶段。试验结束时共计发展了13圈环状裂缝,裂缝最远处距试坑边缘26m。根据室内试验和现场测试结果,建议地区修正系数沿土层深度进行修正,0～10m内β0值取1.05,10～27 m内β0值取0.95。在地表至21 m深度范围内,地基土浸水饱和且湿陷充分,土中竖向应力沿深度呈线性增加,土中竖向应力接近饱和自重应力,21m以下的地基土未能充分湿陷,土中竖向应力逐渐减小。该研究成果可应用于中兰铁路...  相似文献   

基于CMIP5模式鄱阳湖流域未来参考作物蒸散量预估   总被引：3，自引：0，他引：3  

刘子豪  陆建忠  黄建武  陈晓玲  张玲  盛颖东 《湖泊科学》2019,31(6):1685-1697

预测未来气候情境下鄱阳湖流域参考作物蒸散量(Reference crop Evapotranspiration,ET0)的时空分布可为流域水资源的优化管理,为科学应对气候变化对农业生产的影响提供基础数据支撑.利用鄱阳湖流域14个气象站点1961-2014年逐日气象数据,采用Penman-Monteith公式计算出历史ET0;基于同期美国环境中心(NCEP)再分析数据及2006-2100年CMIP5中CNRM-CM5模式在RCP4. 5和RCP8. 5情景下的预测数据,经统计降尺度模型(statistical downscaling model,SDSM)模拟和偏差校正,预测流域未来ET0;通过Mann-Kendall检验、普通克里金插值和空间自相关法分析了流域1961-2100年ET0的时空演变特征.结果表明:NCEP再分析资料与流域ET0建立的逐步回归降尺度模型模拟效果较好,CNRMCM5模式降尺度模拟结果经偏差校正后,精度明显提高,适宜流域未来ET0的预估.鄱阳湖流域在基准期1961-2010年ET0整体上呈减小趋势,空间分布上呈南北高、中间低的特点,表现出明显的空间差异性.RCP4.5、RCP8.5情景下未来3个时期鄱阳湖流域ET0较基准期均呈不同程度的增加趋势,其空间分布整体表现为东高西低、局地略有突出;无论是在基准期或是未来情景下的3个时期,ET0均具有较强的空间自相关性.在RCP8.5情景下,鄱阳湖1961-2100年干旱指数呈现出较为明显的上升趋势,流域的干旱状况随时间加剧,2011-2100年间流域绝大部分地区由湿润区转为半湿润区,干旱指数自南向北递减,赣江流域将是鄱阳湖流域未来干旱风险的重点防范区.  相似文献   

底泥就地稳定化中零价铁(Fe⁰)对有机污染物的作用及其对上覆水体水质的影响     

章萍  相明雪  马若男  刘强  葛刚  钱光人 《湖泊科学》2018,30(5):1218-1224

在实验室模拟静态湖泊体系条件下,通过向实际底泥中投加零价铁(Fe~0),考察反应前后底泥中有机物数量、种类、总有机质含量以及上覆水体溶解氧(DO)浓度、氧化还原电位(Eh)、pH和化学需氧量(CODCr)浓度等指标的变化,探讨Fe~0对底泥有机物的降解效果以及对上覆水体水质的影响.结果表明,投加Fe~0处理80 d后,(1)经GC-MS检测出底泥中易被降解的小分子有机物(分子量小于200)数量明显增多,底泥总有机去除率为44%.(2)上覆水体的DO浓度、Eh和pH都有不同程度的变化.DO浓度从6.6 mg/L迅速下降至0.2 mg/L,Eh从150 mV左右下降至74 mV,pH升高至8.4,此体系易形成厌氧环境;且上覆水体中CODCr低于纯底泥-水体系,上覆水中DO浓度、Eh及pH与CODCr浓度具有一定相关性.综上,底泥中投加Fe~0可有效降解有机物,且不会对上覆水体产生持久、较大的影响.  相似文献   

青藏高原地面有效辐射变化及其对表层土温的影响   总被引：7，自引：6，他引：1  

李韧  赵林  丁永建  沈永平  季国良  刘广岳  杜二计  肖瑶  孙琳婵  刘杨  石伟 《冰川冻土》2011,33(5):1022-1032

利用青藏高原格尔木、狮泉河、昌都日射站及中国科学院冰冻圈观测研究站的观测资料,分析了高原有效辐射的变化,在此基础上结合土壤温度资料讨论了高原北部有效辐射的变化对表层土壤热状况的影响.结果显示：1）青藏高原有效辐射变化因所处的区域不同而异,高原东北部、西部及高原腹地有效辐射总体呈减小的趋势,高原东南部有效辐射呈增大的趋势...  相似文献   

An Exploration of the Interplay between the Measurement Uncertainty and the Number of Samples in Contaminated Land Investigations     

Katy A. Boon  Peter Rostron  Michael H. Ramsey 《Geostandards and Geoanalytical Research》2011,35(3):353-367

In the assessment of potentially contaminated land, the number of samples and the uncertainty of the measurements (including that from sampling) are both important factors in the planning and implementation of an investigation. Both parameters also effect the interpretation of the measurements produced, and the process of making decisions based upon those measurements. However, despite their importance, previously there has been no method for assessing if an investigation is fit‐for‐purpose with respect to both of these parameters. The Whole Site Optimised Contaminated Land Investigation (WSOCLI) method has been developed to address this issue, and to allow the optimisation of an investigation with respect to both the number of samples and the measurement uncertainty, using an economic loss function. This function was developed to calculate an ‘expectation of (financial) loss’, incorporating costs of the investigation itself, subsequent land remediation, and potential consequential costs. To allow the evaluation of the WSOCLI method a computer program ‘OCLISIM’ has been developed to produce sample data from simulated contaminated land investigations. One advantage of such an approach is that as the ‘true’ contaminant concentrations are created by the program, these values are known, which is not the case in a real contaminated land investigation. This enables direct comparisons between functions of the ‘true’ concentrations and functions of the simulated measurements. A second advantage of simulation for this purpose is that the WSOCLI method can be tested on many different patterns and intensities of contamination. The WSOCLI method performed particularly well at high sampling densities producing expectations of financial loss that approximated to the true costs, which were also calculated by the program. WSOCLI was shown to produce notable trends in the relationship between the overall cost (i.e., expectation of loss) and both the number of samples and the measurement uncertainty, which are: (a) low measurement uncertainty was optimal when the decision threshold was between the mean background and the mean hot spot concentrations. (b) When the hot spot mean concentration is equal to or near the decision threshold, then mid‐range measurement uncertainties were optimal. (c) When the decision threshold exceeds the mean of the hot spot, mid‐range measurement uncertainties were optimal. The trends indicate that the uncertainty may continue to rise if the difference between hot spot mean and the decision threshold increases further. (d) In any of the above scenarios, the optimal measurement uncertainty was lower if there is a large geochemical variance (i.e., heterogeneity) within the hot spot. (e) The optimal number of samples for each scenario was indicated by the WSOCLI method, and was between 50 and 100 for the scenarios considered generally; although there was significant noise in the predictions, which needs to be addressed in future work to allow such conclusions to be clearer.  相似文献   

Short-term residence and movement patterns of the annular seabream Diplodus annularis in a temperate marine reserve     

David March  Josep Als  Amlia Grau  Miquel Palmer 《Estuarine, Coastal and Shelf Science》2011,92(4):251-587

The short-term movements of a small temperate fish, the annular seabream Diplodus annularis (Linnaeus 1758), were examined using standard tag-recapture and passive acoustic telemetry in Palma Bay (NW Mediterranean), a marine protected area (MPA). The study aimed to provide valuable information for assessing the recreational fishery and its results suggest that MPAs can be used to protect the adult stock of D. annularis. All the fish tagged with standard tags were recaptured near the release locations, with a maximum distance of ∼300 m. The maximum time between release and recapture was 185 d. Two different arrays of acoustic receivers were deployed, one in 2008 and another in 2009, within the MPA. Twenty adults were surgically tagged with acoustic transmitters. Fish monitored in 2008 (n = 12) were translocated from the point of capture to analyse the movement behaviour after artificial displacement. Upon release at displaced locations, 67% of the fish moved towards the original capture location using a time of return that ranged from 0.75 to 15.25 h. Fish monitored in 2009 (n = 8) were released at the point of capture. They showed high site fidelity with a maximum period of 27 d between the first time and the last time they were detected.  相似文献   

The Reliability of Assigned Values from the GeoPT Proficiency Testing Programme from an Evaluation of Data for Six Test Materials that have been Characterised as Certified Reference Materials          下载免费PDF全文

Philip J. Potts  Michael Thompson  Peter C. Webb 《Geostandards and Geoanalytical Research》2015,39(4):407-417

Assigned values derived from the GeoPT proficiency testing programme were compared with certified values for six certified reference materials that have been used as test materials in the GeoPT programme. Statistical analysis showed that there were few significant differences between these sets of data and that these differences had no significant impact on the GeoPT assessment when fitness‐for‐purpose criteria were taken into account.  相似文献   

Determination of Ga,Ge, Mo,Ag, Cd,In, Sn,Sb, W,Tl and Bi in USGS Whole‐Rock Reference Materials by Standard Addition ICP‐MS          下载免费PDF全文

Richard M. Gaschnig  Roberta L. Rudnick  William F. McDonough 《Geostandards and Geoanalytical Research》2015,39(3):371-379

A procedure for determining a wide range of chalcophile and siderophile elements in typical crustal rocks using standard addition and ICP‐SFMS (inductively coupled plasma sector field mass spectrometry) is presented. New results for Ga, Ge, Mo, Ag, Cd, In, Sn, Sb, W, Tl and Bi abundances in USGS whole‐rock reference materials AGV‐2, BHVO‐1, BIR‐1, G‐2, GSP‐1 and W‐2 are reported using this analytical procedure. Intermediate precision of means based on multiple dissolved aliquots of each USGS reference material was 10% RSD or better for Ga, Ge, In and Sn in all, and similarly good for Ag, Cd, Sb, Tl and Bi in most reference materials. Poorer intermediate precision of Mo and W measurements in several reference materials is probably due to higher analytical blanks on these elements and powder heterogeneity due to a sulfide‐related nugget effect in the specific case of Mo in GSP‐1. Results for all elements fell within the range of available published data with the exception of Ag, which yielded systematically higher concentrations than found in the literature for five of the six reference materials, likely reflecting interference from unresolved polyatomic species.  相似文献